In the field of a spectrophotometer, a device user (manage) regularly manages the performance of the spectrophotometer to check the accuracy of measurement. A method for testing the performance has been defined in the performance indication method (Japan Analytical Instruments Manufacturers Association) of JAIMAS 0001 ultraviolet and visible spectrophotometer, and JIS K0115 general rules for molecular absorptiometric analysis (Japanese Industrial Standards Committee).
The “wavelength accuracy” and the “resolution” have been defined in test items thereof. The “wavelength accuracy” is defined by a wavelength representing a difference (wavelength drift) between an actual wavelength of maximum light intensity of a monochromatic light, which is emitted from a spectroscope with a deuterium discharge tube or a low-pressure mercury lamp as a light source, and a set wavelength of the device. Alternatively, it is defined by a wavelength representing a difference (wavelength drift) between a wavelength at a minimum point of transmittance and the set wavelength, by using a wavelength calibrating optical filter. The “resolution” is defined by representing a wavelength having a spectrum width of a monochromatic light emitted from a spectroscope with the deuterium discharge tube or the low-pressure mercury lamp as the light source. Alternatively, upon measuring the absorption spectrum of a certain substance (e.g.: benzene vapor), the “resolution” is defined by representing a difference in wavelength between neighboring peaks with an extent capable of being separated from each other.
The conventional spectrophotometer has used a deuterium discharge tube and a halogen lamp as a light source that emits a bundle of light rays taken as light to be measured. When determining the “wavelength accuracy”, it is determined by a difference between an actually measured wavelength having a maximum light intensity and each of set bright-line spectrum wavelengths (486.0 nm and 656.1 nm) of a deuterium discharge tube, which is mounted on a device in advance to use for the determination. Even when determining the “resolution”, the bright-line spectrum wavelengths (486.0 nm and 656.1 nm) of the deuterium discharge tube are measured, wavelengths corresponding to ½ of the maximum light intensity are determined on longer and shorter wavelength sides with respect to the maximum light intensity, and a difference between a longer wavelength-side wavelength corresponding to ½ of the maximum light intensity and a shorter wavelength-side wavelength corresponding to ½ of the maximum light intensity is determined, thereby determining the resolution.
Incidentally, for example, Patent Document 1 (Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2000-505555) discloses of using a xenon flash lamp as a light source for a spectrophotometer. The Patent Document 1 discloses that a calibration check on a device is performed using specific bright lines of the spectrum of the xenon flash lamp. Since no deuterium discharge tube or the like is however mounted to the device, the determinations of the “wavelength accuracy” and the “resolution” using the deuterium discharge tube or the like cannot be performed.
Therefore, in the spectrophotometer using the xenon flash lamp, the “wavelength accuracy” or the like is determined by using bright-line spectrum wavelengths (229 nm, 248 nm, 485 nm, 529 nm, 823 nm, 882 nm) of the xenon flash lamp, or optical filters of neodymium filters (e.g., 441.1 nm, 472.9 nm and other seven wavelengths) in which absorption spectra are individually predetermined by the official laboratory, or holmium filters (e.g., 279.3 nm, 2 87.6 nm and other seven wavelengths).